Deep Well Ground bed & Anode System Installation
We design and install Deep Well ground bed and anode systems to distribute impressed electrical current for cathodic protection against corrosion on steel pipelines, underground storage tanks, underground structures, oil and gas well casings.
The below factors are the most considered during the Design phase:
- locations for the ground bed and anode system.
- determine the current required for cathodic protection.
- identify the potential for interference.
- determine the current signal strength.
- identify and select the power supply.
An effective ground bed has anodes installed in a vertical position 50 to 700 feet below the Earth’s surface and using an appropriate drilling location. The site location is determined where the anode system and deep ground bed can be installed to maximize protection against corrosion of underground infrastructure.
The below factors are considered when determining the best site location:
- low soil resistivity formation and measurement of soil resistivity.
- power lines are surveyed to ensure power is available.
- accessible for construction and maintenance.
Deep ground beds are classified as Deep Well ground beds and shallow horizontal anode beds are classified as Surface Level Beds or Shallow Vertical ground beds. Conventional deep anode ground bed systems consist of Discrete or Continuous anodes inside a coke backfill. Anode composition includes graphite, High Silicon Cast Iron (HSCI) and Mixed Metal Oxide (MMO) anodes.
Groundbed Hole Plug and Drilling Rig
Deep Well Anodes and Coke Breeze
A deep well ground bed consist of the active area; bottom of the hole to the top of the coke column, and inactive area; ranging between 50 and 100 feet in depth from the ground surface to the top of the coke surface. With the anodes in a vertical column of low resistance formation, the coke backfill is conducive for current distribution from 20 feet above the last anode to the bottom of the anodes.
Groundbed Junction Boxes and Ventilation Pipe
The Ventilation Pipe is installed in the center of the active area and coke column allowing chlorine gas to escape into the atmosphere. This vent pipe can also be used as a watering system if the active anode column becomes dry. If not vented properly, chlorine gas can cause corrosion and eventual system break down. Cabling is also very important to maintain the connection between the anodes and rectifier, and while being inaccessible after installation. We use either the heavy-duty polyethylene (HMWPE) cable insulation or the more expensive dual insulation that includes a chlorine resistant PVDF layer.
When evaluating the performance of a deep well ground bed, the key issues are size of the active area, resistance soil resistivity, quality of anodes and quality of the coke columns. The design life is calculated based on the quality and quantity of anodes installed and the expiration time based on the assigned current. System life can exceed, or be less than, the Design life based on the quality of design and component installation and operating within recommended guidelines.